In recent years, there have been made developments in each of which a power storage system that uses a power storage device such as a secondary battery or an electric double layer capacitor is applied to a control apparatus for an electric car, and it has been known that kinetic energy possessed by the vehicle can be effectively utilized owing to a configuration in which excess regenerative power generated in the regenerative braking mode of the vehicle is stored and in which the stored power is used in the powering acceleration mode (in, for example, Patent Document 1).    Patent Document 1: JP-A-2006-14395